Spray gun



April 27, 1954 c. H. PARSONS ErAL SPRAY GUN Filed Aug. 30, 1952 iihmiall Patented Apr. 27, 1954 UNITED STATES OFFICE SPRAY GUN New YorkApplication August 30, 1952, Serial No. 307,355

11 Claims. 1

This invention relates to a spray gun, and particularly to a spray gunfor handling materials at elevated temperatures. The spray gun to behereinafter described is particularly adapted for handling low meltingmetals or alloys in molten form, plastics at elevated temperatures, orany viscous material to be thinned by heating.

Spray guns for handling molten metal are particularly susceptible tofreezing of the metal at the nozzle, also to burning of the metal in thegun body due to excessive oxidation of the metal and consequentformation of scum or dross on the surface.

Our new spray gun is characterized by structural simplicity which makesthe same easy to manufacture, assemble, disassemble and clean.Furthermore, our newl spray gun has features therein which make fortrouble-free and satisfactory operation for long periods of time. Otherand additional advantages will be pointed out in connection with thedetailed description of the new spray gun. An exemplary embodiment ofone form of new spray gun embodying our invention will now be describedin connection with the drawings, it being understood that variations inconstruction may be made without department from the spirit of theinvention.

Referring therefore to the drawings:

Figure l is a top plan view of a spray gun embodying our invention;

Figure 2 is a sectional elevation along line 2-2 of Figure l.

The spray gun comprises handle grip I l rigidly attached to gun bodygenerally indicated by numeral i l, from the body of which dependsnozzle assembly i3 and to the side of which there is attached junctionbox l5. Handle l may have any desired shape and is here shown as beingof the pistol grip type.

Handle lo carries pivot pin l1 upon which is carried trigger or controlhandle I8. The movement of trigger handle i8 around pivot l1 is limitedby stop screw i9 and lock-nut 25 mounted in part 2l of the handleextending toward the gun body. Between handle portion 2l and the sunbody generally indicated by numeral ll is housing 23. The bottom ofhousing 23 carries an. air valve having body 24 provided with a suitableinlet fitting 25 for air. Air valve 24 may be of any desiredconstruction and as here shown has valve rod 26 cooperating withspring-pressed valve member 2l. Valve member 2l normally rests againstvalve seat 28 and may be moved to open position by actuation of valverod 25. Valve rod 26 is actuated by plunger 30 which slides in ing ringsto prevent leakage of air. Plunger 3f!` extends above the top of valvebody 24 and is actuated by nger 33 of vertically sldable rod 34 disposedin housing 25. Tip position 35 of the trigger cooperates with finger 33for controlling the valve. The air valve has outlet 3l connected byscrew ttings 33 and pipe 39 to nozzle assembly I3.

Referring now to gun body il, this comprises magazine or tank 40 ofsuitable refractory metal or material. For many purposes, tank 40 may beof stainless steel. Other metals or nonmetallic materials, such asglass, porcelain or ceramic may be used. Tank 40 may have any desiredshape and as shown here has straight sides 4I and 42 with rounded sides43 and 44. The bottom of the tank is stepped and will be described indetail later.

Within tank 4B is electric heating element 46 having coils extending tothe bottom of the tank. Electric heater 46 is metal clad and may be anyone of a number of heaters well known on the market and used in electricstoves and other devices. Generally, such heating elements consist ofresistance wire, such as Nichrome, buried in solidied insulationmaterial and the whole surrounded by metal conduit or pipe. The heatingelement should be capable of withstanding both the temperature and anycorrosive or alloying action of the material heated within the tank.Electric heating element 45 has the two end portions thereof extendinginto junction box l5 for connection to suitable electric receptacles.

Tank 40 has bottom portion 49 adjacent rounded side 43. Bottom portion49 is provided with fittings 5|] and 5| dening chamber 52 within whichis disposed thermocouple 53. Thermocouple 53 is inside of hollow tting5l near the bottom of the tank and will thus be responsive to thetemperature of the heated or molten material in the tank. Thermocouple53 is connected by cable 54 to suitable switch control means formaintaining a desired constant temperature within the tank. Inasmuch assuch thermostatically controlled systems are well known, no descriptionthereof is deemed necessary.

Bolted to opposite straight portions 4I and 42 of the tank is baffleplate 56 extending into tank 40 down 'close to the bottom thereof.Rigidly bolted to baille plate 56, as by a clamp, is thermocouple 5l'connected by cable 58 to an alarm, such as a gong. Thermocouple 51extends for a substantial desired distance into tank 40 and is adaptedto actuate an alarm in the event that the temperature surrounding thetherrnocouple falls to a lower value than normal during operatingconditions. This will occur when the level of the material, such asmetal, becomes too low in the tank. Thermocouple 5l therefore willcontrol a low level alarm system. In addition, the low level alarm willfunction as a supervisory alarm for indicating whether the entire tankheating system is operating.

Bolted between baffle plate 58 and housing 23 is supporting block 8i! ofsuitable metal, such as iron or stainless steel. Block 88 carries pivotpin iii upon which is mounted rocker arm 62. Rocker arm 82 has finger 83extending into housing 23 and disposed within slot 54 of verticallymovable rod 3d. Rocker arm B2 has actuating end 58 pivotally secured at61 to tubular push rod 58. Tubular push rod 58 works in well 18 insupport block El) and the tubular push rod is biased downwardly by coilspring 1l extending between the bottom of the well and anchor block 12within the push rod.

Tubular push rod 58 extends into the tank and should therefore be madeof material, such as stainless steel, to withstand the temperature aswell as any corrosive effects of the material within the tank. Tubularpush rod 88 has the bottom part thereof closed by shouldered plug 14rigidly attached thereto as by a press iit or by welding or the like.shouldered plug 'i4 has axial channel 15 therethrough, the upper portionof the channel being threaded and the lower portion of the channel beingsmooth and reduced in dimension. The threaded upper portion of channel15 accommodates threaded head 15 of needle valve 18. Threaded head 18may be adjusted to any desired position in plug 1li after which stopscrew 8U, extending laterally of the plug, may be tightened to lock thethreaded needle valve head into position.

The bottom of tank 40 bounded by curved side 44 and the right hand partsof straight sides di and 42, as seen from the top in Figure 1, is formedas a downwardly extending circular flange 8| having the outside thereofthreaded. As is clearly shown in Figure 2, flange il extends down belowtank bottom 49 at the left thereof. The entire nozzle assembly I3 isbolted to the bottom of the tank by shouldered ring nut 82.

The nozzle assembly i3 includes generally conical cup member 83 havingan outwardly extending iiange bearing against the bottom of flange 8| ofthe tank and engaged by the shoulder of ring 82 and pressed firmlyagainst the tank. flange. Conical cup 83 of the nozzle assembly ishollow and at the bottom carries inner and outer sleeves 34 and 85.Sleeve 84 has the bottom end counterbored and threaded to receive nozzletip 86. Conical cup 85 and sleeves 84 and 85 are formed of metal, suchas stainless steel, which will withstand the temperature of the moltenor hot material in the gun tank. Cup 83 and sleeve 85 have jacket 81intimately and permanently joined thereto. Jacket 81 is of metal and maybe cast on cup 83 and sleeve 85. For many applications, jacket 81 may beof aluminum. However, it may be of a higher meltting metal or alloy,such as copper or brass, for example, if that is necessary.

Embedded within jacket 81 is electric heating element 88 generally ofthe same construction as heating element 45 for the tank. Heatingelement 88 is preferably disposed on the inside portion of the jacketand close to outer Sleeve 85. Transversely through the jacket is'fitting @dior receiving the end of air pipe 39. Fitting 88 provides anair channel through the jacket and registers with an opening in outersleeve 85. Between outer sleeve and inner sleeve 84 is annular channel9|, through which air passes to the nozzle tip 8,5.

Jacket 81 has chamber 93 near the bottom thereof in which isthermocouple 94 maintained therein by fitting 95. The thermocouple isconnected by cable 96 to a suitable switching sys tem for controllingheater 88 to maintain the nozzle assembly at a desired temperature.

Needle valve 18 has a pointed tip cooperating with the needle valve seatin nozzle tip 85. The outside of the nozzle tip is protected by cap 98carried by ring nut 99 engaging the externally threaded end of nozzletip 88. The construction of the needle valve and various sleeves andseats are conventional. The nozzle tip has a number of air channels |88registering with annuiar air channel 8l.

The entire nozzle assembly including the jacketing may be quicklyremoved from the gun proper by disconnecting air pipe 39 from iitting@il and loosening ring nut 82. It is clear that the needle valve itselfmay be easily adjusted or replaced. Nozzle tip 86 may be changed to varythe air or needle valve discharge openings and thus provide fordifferent gun operation or accommodate different materials to besprayed.

To operate the gun, a quantity of material such as a low melting metalor alloy, such as lead, for example, or tin or any other desiredmaterial, may be dropped into tank 40. The heating elements within thetank will melt the material and maintain the same in molten condition.Baiiie plate 56 will prevent undesired dross or scum from entering theWell of the tank from which material flows to the needle valve. As arule, any metal or material to be melted or heated will be deposited inthe tank to the left of the baille plate 58 as seen in Figure 1 orFigure 2. Preferably, the surface of the molten or hot material iscovered with a layer of inert liquid, such as a high boiling oil or somenoninflammable liquid which will protect the surface of the metal beingmelted, or protect the surface of the material being heated, fromundesired interaction with atmosphere.

Assuming that the gun is properly loaded and is ready for use, triggerI8 is rocked on pivot I1. This causes member 34 to be moved downwardly,opening the air valve and raising the needle from its seat.

The large mass of material forming nozzle assembly I3 provides asubstantial thermal lag and insures proper heating of the air, as wellas a desired temperature of the molten material around the needle valve.Freezing of the needle valve is rendered impossible. In practice, nozzletip 85 may be of copper or brass or other metal having excellent heatconductivity. The threaded part of the nozzle tip extending inwardly ofinner sleeve 84 insures good heat transfer to the nozzle tip and thusinsures the maintenance of desired temperature conditions at the needlevalve seat. If desired, jacket 31 may extend down around the nozzle tipto insure a more intimate connection between the body of the nozzleassembly and the nozzle tip itself.

In order to conserve heat, the outside of the tank may be covered withsuitable heat insulation |03 of material like asbestos. It is alsopossible to cover the nozzle assembly with a heat insulation. Airsupplied to the gun may be preheated.

Instead of loading the gun tank by dropping material therein, it ispossible to have a central supply tank for a number of guns. Each gunmay be connected to the central supply tank by hose having means to heatthe hose to prevent chilling. The central supply tank would have heatingmeans, thermostatic control, and low level alarm as desired. With such acentral tank, each gun could have the molten or hot material feddirectly to the needle valve and the individual gun tank, tank heater,low level alarm and tank thermostat could be eliminated.

We claim:

l. A spray gun for handling material to be maintained at an elevatedtemperature prior to spraying, said gun comprising a body including atank for retaining a quantity of material to be sprayed, electricheating means disposed in said tank for maintaining said material at anelevated temperature, a nozzle assembly carried by said body, saidnozzle assembly including an elongated needle valve member and needlevalve sleeve having an end channeled to provide a seat and dischargeopening for said spray material, an electric heater surrounding saidneedle valve sleeve and a massive metal jacket around said heatingmeans, said jacket having sufficient mass to endow the nozzle assemblywith substantial thermal lag, thermostatic means disposed in said jacketfor controlling the heating element to maintain the nozzle assembly at asubstantially constant elevated temperature, an air supply including adischarge opening adjacent the discharge opening of the sprayingmaterial, said air supply also including an air valve and manual meansfor operating simultaneously both the air valve and needle valve.

2. The spray gun according to claim 1 wherein said air supply includesan inlet through the nozzle jacket and air channels within the nozzleassembly providing air paths through the nozzle assembly.

3. The spray gun according to claim 1 wherein said nozzle assemblyincludes a nozzle tip having the valve seat for the needle valve member,said nozzle tip being removable from the nozzle assembly.

4. The spray gun according to claim 1 wherein said jacket is of castaluminum.

5. A spray gun for handling material to be maintained at an elevatedtemperature prior to spraying, said gun comprising a body including atank for the spraying material, an electric heating element within saidtank, said tank having a two level bottom, a nozzle assembly detachablysecured to the lower tank level and forming the closure therefor, saidnozzle assembly including a cup-shaped member having a depending sleeve,an elongated needle valve member disposed in said sleeve, an actuatingmember carrying said needle valve member and extending upwardly throughthe tank to the top thereof, said nozzle assembly including an electricheating element wound around said sleeve and a massive cast metal jacketaround said heating element and around the outside of said cup-shapedmember, thermostat means carried by said jacket for controlling thenozzle assembly temperature, a nozzle tip detachably secured to thebottom free end of said nozzle assembly sleeve, said nozzle tip having achannel therethrough with a needle valve seat for cooperation with saidneedle valve member, means providing air passages through said nozzleassembly and terminating adjacent the discharge region kof said nozzletip, an air supply coupled to said nozzle assembly air passage means,said air supply including a manually controlled air valve, and manualmeans for simultaneously opening said air valve and moving saidactuating member carrying the elongated needle valve to open the needlevalve.

6. The spray gun according to claim 5 wherein said tank is provided witha vertically disposed baffle extending for a substantial distance intothe tank and dividing the same into two compartments, said baiile havingthe lowest part thereof terminating at a distance above the elevatedtank bottom.

'7. The spray gun according to claim 5 wherein the tank is provided witha vertically disposed baie dividing the same into two compartments, theone compartment having the bottom formed by said nozzle assembly, theother compartment having a, thermostatic means extending upwardly fromthe bottom for controlling the tank heater.

8. The spray gun according to claim 5 wherein said tank is provided witha vertically disposed baiiie extending short of the bottom but dividingthe tank generally into two compartments, one compartment having thebottom formed by the nozzle assembly, and thermostatic means carried bysaid baffle and extending for a substantial distance into the tank, saidlast-named thermostatic means being adapted to function as part of a lowlevel spraying material alarm.

9. A spray gun for handling material to be maintained at an elevatedtemperature prior to spraying, said gun comprising a body including atank for storing a supply of spray material, electric heating means forsaid tank for maintaining said spray material at a desired elevatedtemperature, a nozzle assembly carried by said body and including anelongated needle valve member and sleeve surrounding said elongatedneedle valve member, said sleeve having a channeled portion providing aseat and discharge opening for said needle valve member, said needlevalve sleeve being supplied by spraying material from the tank, an airinlet for said nozzle assembly, an air supply for said inlet, said airsupply including an air valve carried by said gun body, manual means forsimultaneously opening said air valve and said needle valve, electricheating means for said nozzle assembly surrounding said needle valvesleeve for maintaining said nozzle assembly and needle valve at anelevated temperature, said tank having a baflie plate dividing same intotwo compartments, said baille plate being vertical in the normal gunposition with said compartments being in side by side relation and beingjoined near the tank bottom, said needle valve member and sleeveextending from the bottom of one compartment and the other compartmentbeing adapted to receive fresh material for spraying.

10. A spray gun for handling material to be maintained at an elevatedtemperature prior to spraying, said gun comprising a body including atank for storing a supply of spray material, electric heating means forsaid tank for maintaining said spray material at a desired elevatedtemperature, a nozzle assembly carried by said body and including anelongated needle valve member and sleeve surrounding said elongatedneedle valve member, said sleeve having a channeled portion providing aseat and discharge opening for said needle valve member, said needlevalve sleeve being supplied by spraying material from the tank, an airinlet for said nozzle assembly, an air supply for said inlet, said airsupply including an air valve carried by said gun body, manual means forsimultaneously opening said air valve and said needle valve, electricheating means for said nozzle assembly surrounding said needle valvesleeve for maintaining said nozzle assembly and needle valve at anelevated temperature, and thermostatic means disposed in said tanks at apredetermined depth, said thermostatic means being adapted to functionin connection with an alarm system for indicating a loW level ofspraying material.

11. A spray gun for handling material to be maintained at an elevatedtemperature prior to spraying, said gun comprising a body including atank for storing a supply of spray material, electric heating means forsaid tank for maintaining said spray material at a desired elevatedtemperature, a nozzle assembly carried by said body and including anelongated needle valve member and sleeve surrounding said elongatedneedle valve member, said sleeve having a chan neled portion providing aseat and discharge opening for said needle valve member, said needlevalve sleeve being supplied by spraying material from the tank, an airinlet for said nozzle assembly, an air supply for said inlet, said airsupply including an air valve carried by said gun body, manual means forsimultaneously opening said air valve and said needle valve, electricheating means for said nozzle assembly surrounding said needle valvesleeve for main taining said nozzle assembly and needle valve at anelevated temperature, said tank having a vertically disposed bailleplate in the normal gun position to divide the tank into twocompartments disposed side by side, said compartments being connected atthe bottom of the tank below said baie plate and thermostatio meanscarried by said baille plate, said thermostatic means ex tending for apredetermined depth into the tank and being adapted to cooperate with analarm system for controlling the same to indicate a lovv level ofspraying material.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,058,971 Foi-ton Oct. 27, 2,276,232 Gilbert Mar. l0, i9422,434,911 Denyssen Jan. 27, llle 2,5`5l,078 Wing May l., i951 FOREIGNPATENTS Number Country Date 66,337 Norway Mar. 2li, 1942

